1. Field
One or more embodiments described herein relate to a display device and a method for driving a display device.
2. Description of the Related Art
A variety of flat panel displays have been developed. Examples include a liquid crystal display, an organic light emitting diode (OLED) display, and an electrophoretic display. Each pixel of these displays has a field generating electrode and an electro-optical active layer. For example, each pixel of an OLED display has an electro-optical active layer including an organic emission layer, and a field generating electrode is connected to a switching element to receive a data signal. The data signal is converted by the electro-optical active layer to an optical signal to emit light to form an image.
One type of OLED display includes a touch sensor that detects an object approaching or contacting a screen. The touch is detected by sensing, for example, a change in pressure, charge, or light on the screen. This change may be caused, for example, when a user writes text or draws a figure on the screen using a finger or touch pen. When this occurs, an image signal is generated based on touch information.
A capacitive touch sensor includes a plurality of touch electrodes for transferring sensing signals. The touch electrodes may be a mutual-capacitor type or self-capacitor type. When an object approaches or contacts the touch sensor, a change in capacitance or charging amount of the sensing capacitor is generated to sense the touch.
The touch electrodes are disposed in a touch sensing area and connected to touch wires for transferring sensing signals. The touch wires may be inside the touch sensing area and in a non-sensing area around the touch sensing area. The touch wires may transfer sensing input signals to the touch electrodes or transfer sensing output signals generated according to a touch to a touch driver.
The touch sensor may be embedded in the display device (in-cell type), directly formed on an outer surface of the display device (on-cell type), or used by attaching a separate touch sensor unit to the display device (add-on cell type).
A display device having a touch sensor may include a glass substrate. Such a substrate is heavy and fragile and therefore limits portability and is unsuitable for forming a large-screen display. Accordingly, efforts have been made to replace the glass substrate with a plastic substrate, which is lighter, flexible, and able to endure stronger impact. However, when a flexible display stretches, problems may occur, e.g., a malfunction may occur due to a reduction in resolution of the touch sensor. As a result, it may be very difficult to accurately sense a touch under these conditions.